The weak and strong Gaussian probabilistic realization problem

A classification is given of all σ-algebras that make two given σ-algebras conditionally independent in the case that the σ-algebras are generated by finite dimensional Gaussian random variables. In addition a classification is given of all Gaussian measures that have the conditional independence property and such that restricted to a subspace, they coincide with a given measure.     

金属/电介质颗粒复合介质光学双稳的温度效应

应用有效媒质近似，结合自洽平均场理论和谱表示方法，研究了金属电介质颗粒复合介质的光学双稳行为与温度的关系.数值计算了不同的入射频率、体积分数和形状因子下光学双稳的温度效应，结果发现，温度对光学双稳的产生、双稳阈值及阈值宽度有很大影响. 关键词： 复合介质 光学双稳 谱表示 温度     

On the critical behavior of the magnetization in high-dimensional Ising models

We derive rigorously general results on the critical behavior of the magnetization in Ising models, as a function of the temperature and the external field. For the nearest-neighbor models it is shown that ind4 dimensions the magnetization is continuous atT _c and its critical exponents take the classical values=3 and=1/2, with possible logarithmic corrections atd=4. The continuity, and other explicit bounds, formally extend tod>3 1/2. Other systems to which the results apply include long-range models ind=1 dimension, with 1/|x–y| couplings, for which 2/(–1) replacesd in the above summary. The results are obtained by means of differential inequalities derived here using the random current representation, which is discussed in detail for the case of a nonvanishing magnetic field.Research supported in part by NSF grant PHY-8301493 A02, and by a John S. Guggenheim Foundation fellowship (M.A.).     

Statistical replacement for systems with delta-correlated fluctuations

Nonlinear systems with stochastic parameters are approximated by simpler systems using a method that we call statistical replacement. This method is an extension of the previously developed AGREE which was restricted to systems with additive fluctuations. Statistical replacement incorporates the distinctions between globally stable thermodynamically closed systems and thermodynamically open systems that can be unstable.     

基于跨文化视角的旅游地视觉表征差异分析——以中美游客镜头下的西藏为例

旅游地摄影是旅游者自身对目的地的视觉表征,通过潜在游客对目的地的形象感知影响其旅游决策.旅游地摄影被旅游企业视为旅游地视觉营销的重要策略.基于跨文化视角,以中美旅游者拍摄且上传网络的西藏旅游照片为研究对象,采用内容分析法、卡方检验、社会网络分析法和空间分析法,借助NVivo11.0、SPSS22.0、Ucinet6和ArcGIS10.2软件,探寻中美游客摄影图片对西藏视觉表征的差异,以期为旅游目的地定向营销提供参考依据.研究发现：（1）从照片编码树状节点频数来看,雄壮瑰丽的自然景观、虔诚的佛教信徒、神秘的民族非物质文化是西藏旅游形象的核心要素和符号.（2）从照片树状节点类目间差异分析来看,两组照片在自然景观、民族非物质文化、户外活动、舞台化表演和衣饰6个类目上存在统计学差异.中国旅游者的照片更倾向于表征自然景观、当地人生活细节、户外活动和精心设计的舞台化表演.美国游客的照片则更侧重于对原真性的民族非物质文化和绚丽多彩、独特别致的民族服饰的表征.（3）从照片"聚合形象地图"来看,美国样本的聚合形象地图较为复杂和多样化,而中国样本则相对简单有条理.（4）从中美游客地理摄影偏好来看,游客最爱拉萨.除此之外,中国游客更为偏爱那曲地区,而美国游客却更倾向于山南和日喀则地区.     

一种基于特征分解的图像融合方法

一幅图像可以分解成几何特征不同的纹理部分和卡通部分,基于这两大特征提出了一种图像融合方法.利用卡通和纹理特征的差异,通过学习分别得到卡通字典和纹理字典.在融合过程中,分别利用特定的卡通和纹理字典对源图像的卡通和纹理部分进行融合,融合后的卡通和纹理部分经简单相加得到融合图像.实验结果表明,所提方法是有效的.     

面向有限带宽信道的字典学习图像超分辨率重建

固定邻域回归(ANR)算法采用K层奇异值分解(K-SVD)算法进行字典训练, 在字典学习过程中存在稀疏表示系数不准确的问题, 导致重建的结果不理想. 因此, 引入一种改进的K-SVD算法对字典进行训练, 该算法对字典训练改变了传统K-SVD算法更新稀疏表示系数的方式, 使得稀疏表示系数更加准确, 而且加快了字典的收敛速度, 使得训练得到的字典具有更好的稀疏表达能力. 同时, 针对ANR算法的不足, 提出一种面向有限带宽信道基于字典学习的图像超分辨率方法, 该方法采用改进的K-SVD算法训练字典对 , 并将其应用到ANR算法中, 实现图像的超分辨率重建. 实验结果表明, 本文提出的方法不仅能够保持ANR算法快速重建的优势, 而且提高了图像的重建质量, 具有更高的峰值信噪比和结构相似度.     

Application of Bipartite and Tripartite Entangled State Representations in Quantum Teleportation of Continuous Variables

We mostly investigate two schemes. One is to teleport a multi-mode W-type entangled coherent state using a peculiar bipartite entangled state as the quantum channel different from other proposals. Based on our formalism,teleporting multi-mode coherent state or squeezed state is also possible. Another is that the tripartite entangled state is used as the quantum channel of controlled teleportation of an arbitrary and unknown continuous variable in the case of three participators.     

Differential Representations of SO（4） Dynamical Group

In this paper we present systematic differential representations for the dynamical group SO（4）. These representations include the left and the right differential representations and the left and the right adjoint differential representations in both the group parameter space and its coset spaces. They are the generalization of the differential representations of the SO（3） rotation group in the Euler angles. These representations may find their applications in the study of the physical systems with SO（4） dynamical symmetry.